Koreans are generally considered a Northeast Asian group, thought to be related to Altaic-language-speaking populations. However, recent findings have indicated that the peopling of Korea might have been more complex, involving dual origins from both southern and northern parts of East Asia.

To understand the male lineage history of Korea, more data from informative genetic markers from Korea and its surrounding regions are necessary. In this study, 25 Y-chromosome singlenucleotide polymorphism markers and 17 Y-chromosome short tandem repeat (YSTR) loci were genotyped in 1,108 males from several populations in East Asia.

Results: In general, we found East Asian populations to be characterized by male haplogroup homogeneity, showing major Y-chromosomal expansions of haplogroup O-M175 lineages.

Interestingly, a high frequency (31.4%) of haplogroup O2b-SRY465 (and its sublineage) is characteristic of male Koreans, whereas the haplogroup distribution elsewhere in East Asian populations is patchy. The ages of the haplogroup O2b-SRY465 lineages (~9,900 years) and the pattern of variation within the lineages suggested an ancient origin in a nearby part of northeastern Asia, followed by an expansion in the vicinity of the Korean Peninsula.

In addition, the coalescence time (~4,400 years) for the age of haplogroup O2b1-47z, and its Y-STR diversity, suggest that this lineage probably originated in Korea. Further studies with sufficiently large sample sizes to cover the vast East Asian region and using genomewide genotyping should provide further insights.

Conclusions: These findings are consistent with linguistic, archaeological andhistorical evidence, which suggest that the direct ancestors of Koreans were proto-Koreans who inhabited the northeastern region of China and the Korean Peninsuladuring the Neolithic (8,000-1,000 BC) and Bronze (1,500-400 BC) Ages.

Korean Genetic Relationships

Methodology and Results
We analyzed mitochondrial DNA…sequence variation in the hypervariable
segments I and II…and haplogroup-specific mutations in coding regions in
445 individuals from seven east Asian populations…In addition,
published mtDNA haplogroup data…mtDNA HVS-I sequences…Y chromosome
haplogroup data…and Y chromosome STR da…were analyzed to elucidate the
genetic structure of East Asian populations. All the mtDNA profiles
studied here were classified into subsets of haplogroups common in East
Asia, with just two exceptions. In general, the Korean mtDNA profiles
revealed similarities to other northeastern Asian populations through
analysis of individual haplogroup distributions, genetic distances
between populations or an analysis of molecular variance, although a
minor southern contribution was also suggested. Reanalysis of
Y-chromosomal data confirmed both the overall similarity to other
northeastern populations, and also a larger paternal contribution from
southeastern populations.

Conclusion
The present work provides evidence that peopling of Korea can be seen as a complex process, interpreted
as an early northern Asian settlement with at least one subsequent
male-biased southern-to-northern migration, possibly associated with the
spread of rice agriculture.

Last month I posted on the genetic map of East Asia. That paper
surveyed hundreds of thousands of variant loci in the autosomal genome,
and mapped the variation in the populations on a 2-dimensional chart.
Like the genetic maps of Europe there wasn’t too much of a
surprise. So what value-add is there in this sort of study which
examines uniparental lineages, that is, genes inherited only through the
maternal (mtDNA) and paternal (Y) lineages? Here’s the table to look
at:

As you can see, the female lineages are biased toward northern East
Asian lineages, while the male lineages are biased toward southern East
Asian lineages. Uniparental lineages which exhibit sex-based
asymmetries gives us some information in terms of long term demographic
process. Yesterday I blogged a paper about Iceland which
confirms that Icelanders are a mix of British, Irish and Norse, with the
Norse component predominant in the Y lineages and the British &
Irish in the mtDNA lineages. Biases in the origin of male and female
lineages are extremely common in the New World. The authors make
the case that the Y lineages might be evidence of the spread of
agriculture from Southeast Asia. I immediately assumed that before even
getting to their speculation as no other social-historical phenomenon
comes to mind. From Wikipedia:

Mainstream archaeological evidence derived from
palaeoethnobotanical investigations indicate that dry-land rice was
introduced to Korea and Japan some time between 3500 and 1200 BC. The
cultivation of rice in Korea and Japan during that time occurred on a
small-scale, fields were impermanent plots, and evidence shows that in
some cases domesticated and wild grains were planted together. The
technological, subsistence, and social impact of rice and grain
cultivation is not evident in archaeological data until after 1500 BC. For
example, intensive wet-paddy rice agriculture was introduced into Korea
shortly before or during the Middle Mumun Pottery Period (c. 850-550
BC) and reached Japan by the Final Jōmon or Initial Yayoi circa 300 BC.

It’s the intensive period that I suspect might have left a
south-north genetic overlay in the Y. Here’s a close up of a section
of the SNP substructure paper with populations labeled:

The chart is pretty straightforward, though I would note most Chinese
Americans have origins in South China, especially Fujian and the area
around Canton. Taiwanese are mostly Fujianese by origin. Remember this
chart is based on patterns of variation within the autosomal genome,
and displays the two biggest components of variation which can be
extracted out as independent dimensions. The horizontal axis is
somewhat suggestive to me, I have to wonder if the South Chinese,
Koreans and Japanese are further to the left because they have all been
subject to the expansion of rice farmers 2-3,000 years ago. Remember
that the original Han Chinese culture in the Yellow River basin was
based around millet dry farming, the addition of rice agriculture into
the Han culture toolkit was an adoption from the indigenous peoples
south of the Yangtze, many of whom were Sinicized and likely are the
ancestors (at least in part) of the Chinese dialect groups. The
Japanese themselves are a compound, likely of the ancient Jomon peoples
with Siberian affinities, and the later Yayoi rice farmers who arrived
~2,000 years ago, and began in the southwestern islands and slowly moved
east and then north (the Yayoi are the cultural ancestors of the modern
Japanese, though a substantial proportion of Jomon ancestry seems
likely).

Finally, one last comment about the idea that this was a male mediated
migration. One doesn’t need to imagine a male-biased migrant
population. It could be that the original rice farmers who brought the
lifestyle attained a relatively high status among the indigenous peoples
whom they settled. In this case one could imagine that the male
newcomers could leverage their status into reproductive output to a far
greater extent than the females of their group.